Circulation booster



June 4, 1957 J. R. YANCEY 2,794,617

CIRCULATION BOOSTER Filed Nov. 5, 1952 T INVENTOR. 18- i M JOHN RYAIVCEY @MM W United States 2,794,617 CIRCULATION BOOSTER John R. Yancey, Houston, Tex.

Application November 5, 1952, Serial No. 318,860

3 Claims. (Cl. 255-24) This invention relates to the drilling of oil wells, and more particularly to a circulation booster for use with a drill string in the drilling of a well.

As is well known in the art, drill strings are tubular and surface pumps force drill fluid downwardly through the string for emission at the bit and return to the surface in the annular space between the drill string and the walls of the borehole. The thus circulated drill fluid not only serves to lubricate the bit, and sometimes to jet away formation, but also to carry the cuttings back to the surface. it the surface pumps are stopped, however, or the drill string is withdrawn to be subsequently run back into the borehole, the heavy particles in the drill fluid settle out so that the drill fluid becomes extremely dense at the lower section of the borehole. Such extreme density renders it very difficult, in some cases, to reestablish circulation. Further, the deeper the borehole the more resistance to flow of the drill fluid with consequently increasing load on the surface pumps.

In the deeper wells the pressure of the drill fluid in the lower portions thereof becomes so great that sometimes the drill fluid is forced directly into the formation. Such event not only occasions loss of expensive drill fluid but also increases the danger of the drill string sticking in the borehole.

The drill string is usually of considerably smaller diameter than a borehole so that it sometimes becomes rather difiicult, particularly in a deep well, to maintain a straight borehole because of deviations of the bit.

The above problems have been recognized in the art and attempts made to solve them. Devices presently in use, however, for overcoming the aforementioned drilling difiiculties have not proved to be completely satisfactory.

Therefore, it is an objection of this invention to provide an improved circulation booster of increased eflectiveness which is adapted to be attached into a drill string at any point along the length thereof for assisting the surface pumps to reestablish and/or maintain circulation of the drill fluid, several such boosters being usable at various points in the drill string, their number depending upon borehole conditions, the type of drill fluid used, and the depth of the well.

It is another object of this invention to provide an improved circulation booster which reduces the pressure of the drill fluid on the formation in the lower portions of a borehole by increasing the velocity of the return flow of such fluid.

It is another object of this invention to provide an improved circulation booster, of the type under consideration, which also stabilizes the bit, i. e. stabilizes the drill collar by holding it in the center of the hole to both hold the bit in position to drill a round hole and to prevent buckling of the drill collars. Further, such centering of the drill collars improves drill fluid circulating conditions.

It is another object of this invention to provide an improved circulation booster which reduces turbulence of the drill fluid in the annular space between the drill 2,794,617 Patented June 4 1 857 string and the walls of the borehole and also exerts a positive upward force on the drill fluid in such space.

It is a further object of this invention to provide an improved circulation booster for accomplishing the fore going objects which not only is economical to draw facture but also easy to couple into a conventional drill string. 7

Other objects and advantages of this invention will be evident from the following description and accompanying drawings in which:

Figure l is a vertical sectional view through the lower section of a borehole illustrating a circulation booster embodying this invention connected to a conventional drill string within such hole.

Figure 2 is an enlarged fragmentary view, partly in vertical section, through the improved circulation booster embodying this invention.

Figure 3 is an enlarged transverse sectional view taken on line 3-3 of Figure 1.

Figure 4 is an enlarged transverse sectional view taken on line 44 of Figure l.

Figure 5 is an enlarged elevational view of the impeller shown in Figure 1.

Referring now to the drawings, there is shown in Figure l the lower end of a tubular drill string 10 in a borehole 12. Connected to the lower end of the drill string 1%), by a sub 14, is a circulation booster 16 embodying this invention. To the lower end of the circulation booster is connected a conventional jet-type bit 18. A conventional reamer 20 may be connected between the bit 18 and the lower end of the circulation booster 16. Although a single circulation booster embodying this invention has been illustrated in Figure l as being corrnected adjacent the lower end of a drill string, it will be realized that a plurality of such circulation boosters may be connected into a conventional drill string at any location along the length thereof.

Referring now to Figure 2 of the drawings, the circulation booster 16 comprises a tubular mandrel 22 having its opposite ends adapted to be connected into a drill string for passage of the drill fluid downwardly through the central passageway formed in the mandrel. For example, and as shown in Figure 2, the upper end of the mandrel 22 may be provided with an interior pipe thread 26 for reception of a complementary thread 28 on a reduced extension 30 of the sub 14. The lower end of the mandrel 22 may be provided with any type of thread (not shown) for coupling the same to the reamer 20, or to another sub (not shown) or to another section of drill pipe (not shown).

The upper section 32 of the mandrel 22 is of reduced diameter forming an upwardly-facing shoulder 34. Mounted between the ends of this section 32 is an impell'er 36 of a diameter preferably only slightly less than that of the borehole 12. The impeller 36 is fixed to the mandrel section 32, as by a key 38 (Figure 2), for rota tion by and with the mandrel 22, which in turn is rotated by the drill string 10. The impeller 36 has a central hub '40 from which project a plurality of circumferentially-spaced radial vanes 42. Each vane has a concavely curved forward face 44 which, from its lower edge is inclined rearwardly with respect to the direction of ma: tion, as shown by the arrow in Figure 4; The generative elements of this forward face 44 are substantially radial so that rotation of the impeller 36 exerts an upward thrust or force to positively move drill fluid upwardly in the annular space 46 between the drill string 10, and the mandrel 22, and the walls of the borehole 12. The rear face 48 of each impeller vane 42 desirably is somewhat convexly curved in order to provide adequate space for upward passage of the drill fluid between adjacent vanes.

Rotatably mounted on the reduced upper section 32 of the mandrel below the impeller 36 is a tubular guide member 50 having a substantially circular periphery and of a diameter slightly greater than that of the impeller 36. The lower end of the guide member 50 rests against the shoulder 34 formed on the mandrel 22, while the upper end of the member has a short reduced tubular extension 52 which bears against the hub 40 of the impeller to form a bearing surface for the latter. Obviously this reduced extension 52 of the guide member 50 could be replaced by a separate thrust washer (not shown) or the like. The outer surface of the guide member 50 is provided with a. plurality, eight as shown in the drawing," of circumferentially-spaced longitudinal grooves 54 each having substantially parallel side walls and a flat bottom wall, The depth of the grooves 54 preferably is substantially equal to the difference between the radius of the guide member 50 and the major radius of the mandrel 22, and the upper ends of the grooves terminate slightly below the impeller 36. Rotatably mounted on the reduced section 32 of the mandrel above the impeller 36 is another guide member 56 identical to the first-described guide member 50, but inverted with respect thereto. The upper end of the upper guide member 56 bears against a downwardly-facing shoulder 58 formed on the sub 14, so that both guide members 50 and 56 and the impeller 36 are fixed against relative axial movement on the mandrel 22.

The peripheral surfaces of both guide members 50 and 56 are adapted to engage the side walls of the borehole 12 to maintain the members substantially fixed against rotation during the rotation of the drill string 10, and the mandrel 22, in a drilling operation, while the lower end of the member 56 and the upper end of the member 56 are bevelled, as at 60, to facilitate introduction and Withdrawal of the circulation booster 16 into and from the borehole 12.

In operation of the improved circulation booster 16 the drill string 10, with the circulation booster and a bit connected thereto, is run into a bore-hole, the surface pumps started, and the drill string rotated to drill into formation. Since the diameter of the guide members 50 and 56 is sufficient to engage the sidewalls of the borehole, the guide members remain substantially stationary except for down ward movement with the drill string as the bit cuts away formation during the drilling operation. The impeller 36, however, rotates with the drill string 10 and exerts an upward force on the drill fluid passing upwardly from the bottom of the borehole 12 in the annular space 46 between the drill string and the side Walls of the borehole 12. Since the grooves 54 in the guide member 50 and 56 are bridged by the sidewalls of the borehole, these grooves form longitudinal passageways, which in the lower guide member 51] serve to direct the drill fluid into the space between adjacent impeller vanes 42 so that such vanes may positively act on the fluid to force it upwardly. Likewise, the longitudinal passageways in the 7 upper guide member 56 receive the upwardly-thrust drill fluid and smoothly direct it upwardly for passage to the surface. The effect of the aforedescribed construction is that of a pump in which the two guide members 54} and 56 plus that portion of the walls of the borehole 12 surrounding the impeller 36 constitute a pump housing. Hence, drill fluid may be acted upon effectively by the impeller 36 and a positive upward force imparted thereto without undue turbulence.

It also will be noted that the two guide members 50 and 56 serve to stabilize the reamer 20 and the bit 18 in order to prevent drifting of these cutting implements. Further, the above-described pumping action exerts a downward reaction force on the'bit 18 which serves to counteract to some extent the upward force exerted on the drill string 10 by the drag of fluid thereon in passing upwardly in the annular space 46 between the drill string and the Walls of the borehole.

It thus will be seen that the objects of this invention have been fully and eflectively accomplished. It will be realized, however, that various changes may be made in the specific embodiment shown and described to disclose a the principles of this invention without departing from tion comprising: axial-flow impeller means mounted coaxially on the string for rotation therewith to impel drill fluid upwardly in the space between the string and the walls of a borehole, said impeller means being of a diameter slightly less than that of the borehole; and a pair of circular members rotatably mounted on the drill string on opposite sides of said impeller means and closely adjacent thereto, said members being of slightly greater diameter than that of said impeller means for engagement with the Wall of the borehole to prevent their rotation with the string and having longitudinal straight passages therethrough for upward flow of drill fluid through said impeller means, whereby said members stabilize the drill string, and said members and the side wall of a borehole constitute a pump housing for said impeller means and the latter augments drill fluid circulation.

2. A circulation booster and stabilizer for use with a tubular drill string down through which drill fluid is forced comprising: a tubular mandrel having means at the opposite ends thereof for connecting said mandrel into a tubular drill string for rotation therewith and for flow of drill string fluid through said mandrel; a metal axial-flow impeller coaxially fixed on said mandrel between its ends for rotation thereby to urge drill fluid discharged from the lower end of the drill string upwardly in the space between the latter and the walls of an uncased borehole; and a pair of circular metal guide members rotatably mounted on said mandrel on opposite sides of said impeller and closely adjacent thereto, said guide members being of slightly greater diameter than that of said impeller and having peripheral surfaces adapted for engagement with the wall of a borehole for preventing rotation of said members, said members further having means defining straight longitudinal passages therethrough for passage of drill fluid to and from said impeller, whereby said members and the wall of a borehole constitute a pump housing for said impeller.

3. The structure defined in claim 2 in which each guide member is of greater axial length than that of the impeller and has a substantially-cylindrical outer surface provided with a plurality of circumferentially-spaced grooves which define the passages, a short section of the opposite ends of said guide members being tapered to facilitate running-in and pulling-out of the drill string.

References Cited in the file of this patent UNITED STATES PATENTS 682,939 Ivens Sept. 17, 1901 691,123 Farwell Jan. 14, 1902 1,536,754 Benson May 5, 1925 1,746,889 Fitzer Feb. 11, 1930 2,148,740 Fuqua Feb. 28, 1939 2,634,101 Sloan Apr. 17, 1953 

